Well-Known Member

2h of flight time in an electrically powered Ranger, makes electric flight interesting.

When ever there is the talk for high performance clean design requirements, this nonsense for the Ranger, as this bird is a flying barn door, and its never going to be something else then a flying barn door.

So, let’s think about the tech required to make this barn door flying electrically powered for 2 hours.

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40kWhr of batteries should do it.
You'll struggle to build a battery pack under about 200kg. That will mean a higher gross weight, which will need an even larger battery. Your solar wing would knock 10% off the battery.

It is not currently possible to build a 2hr endurance electric Ranger. This is why people who do the maths drone on about the necessity of efficient airframes... Its nonsense trying to scheme a 2 hour endurance electric ranger. Barn doors make awful electric planes.

If you really want an electric ranger, you will have to change the airframe and target. Stretch the span out and settle for an hour, and you have something feasible.

Well-Known Member

40kWhr of batteries should do it.
You'll struggle to build a battery pack under about 200kg. That will mean a higher gross weight, which will need an even larger battery. Your solar wing would knock 10% off the battery.

It is not currently possible to build a 2hr endurance electric Ranger. This is why people who do the maths drone on about the necessity of efficient airframes... Its nonsense trying to scheme a 2 hour endurance electric ranger. Barn doors make awful electric planes.

If you really want an electric ranger, you will have to change the airframe and target. Stretch the span out and settle for an hour, and you have something feasible.

Well-Known Member

No I just have used the most most suitable planform using 30% efficient cells.

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Here is what a real 14KW system looks like:

Due to an errant golf ball and a sympathetic solar company I know those panels each cost $300. I will let you count the panels. How does that fit into your build budget? And is your hanger big enough? Will you fly on bright, mid summer days around noon time? No? Then subtract substantial amounts of energy production! I know because I watched it like a hawk to make sure my math would add up and it did. A $20,000 system after tax rebate that will never pay off!

BTW: Our landlord put this monstrosity in 4 years ago over my protests to serve the farm of which we are renting the house. He really thought he was helping us out but zero savings since the buyback program knocked us out of the county co-op program. In fact, we just paid the most ever for electric last year in the 10 years we have been here! Its not as easy as you make it sound!

Well-Known Member

Due to an errant golf ball and a sympathetic solar company I know those panels each cost $300. I will let you count the panels. How does that fit into your build budget? And is your hanger big enough? Will you fly on bright, mid summer days around noon time? No? Then subtract substantial amounts of energy production! I know because I watched it like a hawk to make sure my math would add up and it did. A $20,000 system after tax rebate that will never pay off!

BTW: Our landlord put this monstrosity in 4 years ago over my protests to serve the farm of which we are renting the house. He really thought he was helping us out but zero savings since the buyback program knocked us out of the county co-op program. In fact, we just paid the most ever for electric last year in the 10 years we have been here! Its not as easy as you make it sound!

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You are quite right..I asked the company who provided the cells for Solar Impulse a 1 m2 piece...I never even got an answer from them.

NASA and others have access to 30 % efficient film thin panels. Just 3 m2 would provide 1 KW in extra push at optimal conditions.

Well-Known Member

FYI, I took that pic at 1:30 this afternoon and in direct sunlight it was producing 7100 watts. When it was new 4 years ago it would have easily produced over 12KW. I saw it with my own eyes. So it shows the degradation of the cells. The cells have a 15 year or so lifespan where they will produce useful energy then are considered defunct. Will you buy new panels every 4 years to keep the energy production where it needs to be?